Add extra newline after <?php in saver classes

* Add extra newline after `<?php` in src/TranslationSaver.php
* Add extra newline after `<?php` in src/SourceSaver.php

Author: didier-84

src/SourceSaver.php

@@ -60,6 +60,7 @@ public function call($sourceEdit, $sourceLocale)
             // Leave the extra newline at the end
             $fileContent = <<<'EOT'
 <?php
+
 return {{translations}};
 
 EOT;

src/TranslationSaver.php

@@ -71,6 +71,7 @@ private function save($locale, $group, $translations)
         // Leave the extra newline at the end
         $fileContent = <<<'EOT'
 <?php
+
 return {{translations}};
 
 EOT;